Shell core forming apparatus



May 25, 1965 G. w. STEWART 3,184,809

SHELL CORE FORMING APPARATUS Filed Aug. 29, 1962 2 Sheets-Sheet 1 FIG. 2

INVENT OR. GEORGE STEWART A T TORNEYS y 25, 1965 G- w. STEWART 3,184,809

I SHELL CORE FORMING APPARATUS Filed Aug. 29, 1962 2 Sheets-Sheet 2 GEORGE W STEWART BY pwm $1M A r roe/v5 rs United States Patent 3,184,809 SHELL CORE FORMING APPARATUS George W. Stewart, 948 Regal Road, Berkeley, Calif. Filed Aug. 29, 1962, Ser. No. 220,212 3 Claims. (Cl. 221t)) This invention relates to apparatus for making shell cores and shell molds for use in making metal castings. It will be understood that the description of the invention with respect to shell cores is equally applicable to shell molds which differ only in that the latter are made in generally concave form for receiving molten metal therein whereas the former are generally convex in form and are used as patterns or cores in casting operations. Both shell cores and shell molds are formed in pattern boxes, which contain a pattern or cavity into which a composition of fine sand and a thermosetting binder is blown and then cured to form a core or mold having sharp and clearly detailed features. A core thus formed consists of a shell of hardened sand the outside configuration of which provides the shape for a cavity-in a casting.

It is an object of the present invention to provide apparatus for making shell cores and molds of more intricate and unusual shapes and designs than heretofore possible.

It is another object of this invention to provide a shell core forming machine which cures the mold as it is being formed, resulting in reduced operating time and increased efiiciency and production of the machine.

A further object of the present invention is to provide a shell core forming machine affording greater maneuverability and ease of handling of the pattern carrying box than heretofore possible.

Yet another object of this invention is to provide a shell core forming machine which allows the excess forming material to be easily discharged from inside the shell prior to removal of the formed shell core from the pattern box.

A still further object of this invention is to provide a shell core forming machine having heating means, for curing the core, carried by the means supporting the pattern box, for simultaneously forming and curing the shell core.

Still another object is the provision of shell core or mold forming apparatus supported and balanced for easy manipulation through the steps in the process of forming shell cores or molds of relatively large size.

It is yet another object of this invention to provide shell core blowing apparatus which is automatically recharged with molding material between formation of successive shell cores.

These and other objects and advantages of the present invention will become more readily apparent and more fully understood in the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of the shell core forming apparatus of this invention, shown in a position for forming or blowing a core;

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1 with the pattern box removed, shown in an inactive position;

FIG. 3 is a greatlyenlarged sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is an enlarged fragmentary elevational view as seen substantially along the line 4-4 of FIG. 1;

FIG. 5 is an enlarged sectional view taken along the line 5--5 of FIG. 1.

Generally, the shell core forming apparatus of this invention comprises a frame having a reservoir thereon for molding sand. The reservoir includes an inclined 3,184,822 Patented May 25, 1965 cover plate having discharge ports therein. An air supply assembly including an actuating valve provides means for discharging the sand from the reservoir through the discharge ports.

A pattern carrying box with one end surface thereof having an inlet opening therein is releasably held by clamping means for movement between release and clamping positions caused by pneumatically powered actuating means. The clamping means and the actuating means are supported by support means for balanced swinging in a generally horizontal plane and for tilting about a generally horizontal axis to incline the end surface of the box at an angle corresponding to that of the cover plate to register the inlet opening with the discharge ports in the cover plate for admitting sand to said opening.

Referring to the drawings, and more particularly to FIG. 1 thereof, the shell core or mold forming machine of this invention is indicated generally at 10, and includes a lower frame 11 and an upper frame 12 securely connected thereto.

A hopper 13 (FIG. 5) for carrying a supply of molding material is secured to frame 12 (FIG. 1) and has depending downwardly from the bottom thereof an inlet tube 14. Telescopically received on tube 14 is a tubular sleeve 15 connected thereto by means of a screw 16 for adjusting the length of sleeve 15 projecting downwardly from the end of tube 14. The lower portion or discharge end of the sleeve 15 terminates in a discharge opening 15a and extends into a chamber 17 having an open upper end and a bottom wall 85 closing its lower end.

The wall 85 defines the top wall of a reservoir 22, and has an opening 18 therein. The discharge opening 15a of sleeve 15 is adjacent opening 18 for conveying sand by gravity to the reservoir 22 from the hopper 13. The opening 18 is closable by a closure 19 connected to a rod 20 and actuatable between open and closed positions by a lever arrangement indicated at 21 in FIG. 1.

The reservoir 22 is an enclosed chamber of generally J-shaped cross section (FIG. 5) having an upstanding leg portion 5 into which the sand from the hopper 13 feeds and a connected horizontal portion 6. The open end of portion 6 remote from portion 5 is directed generally upwardly and has a cover plate 23 secured thereto. The upper surface of plate 23 is preferably inclined, slanting outwardly downwardly from reservoir 22 toward the front of frame 11 on which said reservoir is supported. Plate 23 is provided with a plurality of discharge ports 24 therein communicating with the interior of reservoir 22.

The rear portion 5 of reservoir 22 communicates with a source of air under pressure, indicated at 25, by means of a conduit 26 in the upper end of portion 5 adjacent the opening 18. The pressure under which the air enters reservoir 22 may be regulated by a conventional valve assembly 27 positioned between the conduit 26 and the air supply 25 for'discharging the sand from the reservoir through the discharge ports 24 in plate 23.

The reservoir is automatically refilled between discharges by the cooperation between the sleeve 15 and the opening 18. When the closure 19 is in the open position shown in FIG. 5, sand flows by gravity from hopper 13 ing a of sleeve 15 and stopping the flow of sand. It is to be understood that prior to admitting air from air supply into reservoir 22 the closure 19 must be 'moved to a closed position to prevent sandfrom being inlet opening 81 provided therein through which the mold. mg sand is admitted to the cavity 29. Box 23' is swingably and tiltably supported for positioning the surface 80 in engagement with the cover plate 23 and the inlet open-.,

ing-8l in registration with the ports 24 for admitting the sand from the reservoir 22 into the cavity 29.

A first support means (FIGS. 1, 2) for swingably supporting the box 28 about a vertical axis is carried by a trunion assembly 31 (FIG. 3) comprising a T-shaped 'member 32 pivotally supported on a vertical pivot post It is to be understood that a box carrying a pattern 33 extending upwardly into the hollow leg 82 of memi 'ber 32. A conventional thrust bearing 34 is seated between the upper end of pivot post 33 and the upper end of leg 82. A conventional ball or rolling bearing member 35 is seated between the lower end of pivot post 33 and the lower end of leg 82 to ensure smooth pivotal I movement of member 32 about the post 33. The lower end of the post 33 is securely attached to a plate 36 (FIGSI l, 2) which is slidably supported in a base 37 for lateral ad ustment of support member 30 relative to the frame ll. The plate 35 is moved within the base 37 by means of a conventional crank arrangement, indicated at 38.

The crosshead S3 of T-shaped member 32 is hollow to receive therein a hollow shaft 39 which is an integral extension of an oval shaped casting 40. The shaft 39 and,

casting 4d are supported for rotation by means of a plurality of bearings 41. The casting 40 has a pair of parallel extending guide arms 42 cantilevered therefrom which in turn support the clamping means for the pattern carrying box 28.

The clamping means for the box half 28a" (FIG. 4)

- Compris s a substantially fiat plate 43 which is securely connected to the terminal ends of the arms 42 by means of lock nuts 44. The plate 43 has connected thereto a gas burner member 45 which is supported on the arms 42 by a pair of opposed, outstanding ears 46 (FIG. 5). The inner face of member 45 adjacent box half 28a has a plurality of gas ports '47 therein which communicate with a source of fuel gas(to.be later described). The

' member 45 has a'pair of vertically extending flanges 48 for securely mounting the box half 28a thereon.

The clampingrneans for the box half 281) comprises a plate 49 which is connected to a gas burner member 50.. Plate 49 and member 50 are: identical with plate 43 and member 45, respectively, except that theformer are rei versed relative to the latter, andare adapted to slide along. the arms 42 to thereby move boxhalf 28b in opening and closing relation to box half 28a for permitting removal of the cured core from the cavity29. V

The apparatus for moving box half 28b relative to box half 28a comprises an air cylinder 51 (FIG. 3) cantile v- "eredfriorn the 'oppositeside of member-32 from the casting 4%, and having a piston 52 and'connected piston rod 53 slidably mounted'therein. The rod 53 extends through the crosshead 83 of member 32'and the end thereof remote ,from piston 52 is securely connected to the plate l 51 is connected to air supply tank 25 by means of air hoses 54, 55 for moving piston 52in either direction.

An adaptor 56"is securely connected to one end of cylinder 51 by a plurality of bolts 57. The adaptor 56 is securely connected by bolts 58 to the end of the shaft 39 remote from the casting 4G, and has an axial-aperture 59 therein through which the piston rod 53' slidably extends. Thus the casting 4b and shaft 39 comprise a second support means for supporting the clamping means for the box halves 28a, 28b for tilting about a generally hori- Zontal axis through 360.

A spring urged detent pin 60 (FIG. 3) is mounted in the crosshead 83 adjacent the casting 40 for-cooperating with a plurality of spaced recesses 60a in the face of the casting 40 for selectively positioning said casting and box halves 28a and 28b carried, by the clamping means at a particular angle of tilt about the axis of piston rod 53. One of the detent recesses 60a is preferably positioned so that when engaged bydetent 6tlthesurface 80 of box halves28a, 2811 containing inlet 31is at the same inclination to the horizontal as plate 23. e

The arrangement whereby the. actuating meansqand the clamping means are cantilevered fromopposite sides of member 33 provides for balanced swinging of said means about a vertical axis defined by post 33. This arrangemcnt affords such maneuverability and ease of handling of the box 28 through the, various steps of the forming process to permit forming of shell cores of relatively large size. l

The system for supplying fuel gas to the gas burner members 45, 50is' illustrated in FIG. *1. A conventional fuel gascarburetor 61 iissupportedon the framell and connected to-a supply of fuel gas- (not shown). A cen- -trifugal blower .62 is mounted on the frame ll adjacent the carburetor 61 for forcing the air and gasmixture from the carburetor 61 through fuel hose 63 connected by a flexible coupling 64 ton pair. of fuel lines 65, 66 which are supported on the top of air cylinder 51 by a pair of brackets'67, 168. A flexible hose 69connects the end of the fuel line 6 5 to the burner member itlforsupplyingthe fuel gas mixture to gas p'orts47. A fuel line 70 connects at one end thereof to the fuel line 66. and

, terminates in a flexible hose 71 connectedto the burner member 45 for communicationwith the gas port 47.

' Suitable ignition and flame control means (not shown) are provided on the burner members 45,50 in .a conventional manner. 1 i

When the surface 80 containing the inletopening 81 to cavity 29 is in engagement with the plate 23 (FIGS. 1, 5),-a locking means, indicated at 72 in FIG. 2, is'provided to maintain such engagement during a core 'forrniug operation.

The locking means 72 Iis mounted on the frame 11 and comprises a support 73"supporting a lever 55 arm,74 whichis pneumatically actuated between locking and release positions. A lock frame is, securely positioned on the plate 43Lfor engagementwith the support 73 when the surface :is in engagement withv theplate 23. The arm 74 in its locking position (FIG. 4) clamps the lock frame 75 .to the support 73.;

The means for actuating the apparatus ofthis inventioncomprises a plurality of standard, pneumatic valves conveniently mountedfon the frame 12(FIGI1). A valve handle '76 controls'a valve (notshown) for operatvingthe.ai'rTcylinder 51,-to move box half 28b between 'opemand clamped positions relative-to boxlhalf128a. Aj

, valve handle .77. operates avalvetnot shown) for simul- 49 (FIG. 4) for moving plate 49, member 50, and box"v half 280 along the guide arms 42, responsive to movement of the". piston 52 Within the air cylinder 51. The cylinder 1 taneouslyfactuating the locking ineans 72. and the closure 19 in :the reservoir 22.; A'valve handle v.78 actuates a yalve (not shown) conneetedto the valve 27"forblowing air. form air supply 25 into reservoir 22.

A standard mechanical vibrator (not' shown) is mounted on the box half28b,in.a conventional manner '.to faciltate removal of the core from thecavity29,'- and is actuated by a lever 79 (F1611 ;In operation, the operator of themachine secures box;

halves 28a, 28b in their respective clamping means. He then moves the valve handle 76 to actuate the air cylinder 51 for moving box half 28!; into clamping position with box half 28a. The support member 30 is manually pivoted about the vertical post 33 in a horizontal plane and the box 28 is tilted about a horiznotal axis to engage the surface 80 with the plate 23 for registering the inlet opening 81 of cavity 29 with the discharge ports 24.

The closure 19 in the reservoir 22 is initially in the position shown in FIG. 5 to allow the reservoir to be filled with sand. The operator moves the valve handle 77 to the on position to actuate the locking means 72 to therby lock the surface 80 of box 28 in engagement with plate 23 and to simultaneously close the opening 18. At this "time the valve handle 78 is moved to the on" position to actuate the valve 27 and admit air under high pressure into the reservoir 22 for blowing sand through the ports 24 to fill the cavity 29. When the cavity 29 is filled with sand the valve handle 78 is moved to shut off the supply of air to the reservoir 22, and the valve handle 77 is moved to the off position to simultaneously unclamp the locking means 72 and open the opening 18. The reservoir 22 is automatically refilled with sand from hopper 13, as previously described.

Throughout the entire operation of the machine the ignited gas burner members 45, 50 continuously heat the box halves 28a, 28b, respectively. This heat melts the thermosetting binder in the sand immediately adjacent the I sides of the cavity 29 to bind the sand and thus form the shell core. The thickness of the core being formed is determined by the length of time which the sand is exposed to heat. When the operator estimates that the core is of the desired thickness, he swings the support member 30 about post 33 away from the plate 23 to thereby allow the excess, loose sand to flow out of cavity 29 on to the ground. The support member 30 may be tilted about a horizontal axis a suflicient amount to remove all the excess sand from the interior of the cavity. Since the support member 30 is tiltable through 360 about a horizontal axis, it will be appreciated that all the excess sand may be dump from the cavity 29 in this easy manner.

When the excess sand has thus been removed from the cavity, the core formed in the cavity continues to cure until the operator estimates that the core is of a desired hardness. A this time he may actuate the vibrator by means of the lever 79 to loosen the core from the walls of the cavity 29. The valve handle 76 is then moved to the open position to separate the box half 28b from box half 28a for removal of the finished core from the cavity changes therein may be made Within the skill and understanding of persons skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. Shell molding apparatus comprising:

(a) a reservoir for molding sand including an inclined cover plate having discharge ports therein;

(1;) means for discharging sand through said ports;

(0) clamping means releasably holding a pattern box having an end surface with an inlet opening provided therein;

(d) support means supporting said clamping means for swinging said box with said surface in a generally horizontal plane intersecting said cover plate and for tilting said box about a generally horizontal axis for positioning said pattern box with said surface and said cover plate in engagement and said inlet opening and said discharge ports in registration for admitting sand to said opening.

2. The apparatus of claim 1, including:

(e) locking means for releasably locking said clamping means with said pattern box in such position.

3. In shell core and shell mold forming apparatus:

(a) a pair of clamping means mounted for movement between release and clamping positions for clamping a pattern carrying box therebetween;

(b) actuating means for moving said clamping means between said positions;

(c) first support means mounted for swinging about a vertical axis and supporting said clamping means and said actuating means cantilevered from opposite sides thereof;

(d) second support means supporting said clamping means for tilting about a generally horizontal axis through at least (e) said actuating means including double acting cylinder means connected to one of the clamping means of said pair having a piston rod extending along said horizontal axis and connected to the other of said clamping means;

(f) guide means supporting said other clamping means for movement toward and away from said one clamping means and connecting said one clamping means said to cylinder means.

References tilted by the Examiner UNITED STATES PATENTS 2,538,770 1/51 Fea 22-10 2,763,902 9/56 Peterson 22-10 2,832,107 4/58 Weaver 22-10 2,852,818 9/58 Shallenberger et a1. 22-10 2,858,585 11/58 Urbanke et al 22-10 2,929,119 3/60 Ronne 22-10 FOREIGN PATENTS 880,853 10/61 Great Britain.

MICHAEL V. BRINDISI, Primary Examiner. MARCUS U. LYONS, Examiner. 

1. SHELL MOLDING APPARATUS COMPRISING: (A) A RESERVOIR FOR MOLDING SAND INCLUDING AN INCLINED COVER PLATE HAVING DISCHARGE PORTS THEREIN; (B) MEANS FOR DISCHARGING SAND THROUGH SAID PORTS; (C) CLAMPING MEANS RELEASABLY HOLDING A PATTERN BOX HAVING AN END SURFACE WITH AN INLET OPENING PROVIDED THEREIN, (D) SUPPORT MEANS SUPPORTING SAID CLAMPING MEANS FOR SWINGING SAID BOX WITH SAID SURFACE IN A GENERALLY HORIZONTAL PLANE INTERSECTING SAID COVER PLATE AND FOR TILTING SAID BOX ABOUT A GENERALLY HORIZONTAL AXIS FOR POSITIONING SAID PATTERN BOX WITH SAID SURFACE AND SAID COVER PLATE IN ENGAGEMENT AND SAID INLET OPENING AND SAID DISCHARGE PORTS IN REGISTRATION FOR ADMITTING SAND TO SAID OPENING. 